Rubber ball



F. T. ROBERTS 2,131,756

RUBBER BALL Original Filed Oct. 6, 1953 2 Sheets-Sheet 1 Jaw/y 7 WWW 3%79%;, K /M SEW Oct. 4, 1938. I T, ROBERTS 2,131,756

- p RUBBER BALL Original Filed Oct. 6, 1933 2 Sheets-Sheet 2 PatentedOct. 4, 1938 a UNITED STATES PATENT Application Octoberfi, 1933, SerialNo. 692,388

Renewed June 12, 1937 '16 Claims. (01. 273-61) "This invention relatesto a ball, suitable for use My invention is illustratedin the drawingsin athletic games, particularly the type used for hereof, which disclosethe ball in various stages playing tennis and similar games; ofmanufacture and invarious modifications, and

r copending application Serial Number thereby illustrate also the methodof manufac- '5 504N67 filed December 26th, 1930 (now P'atent ture. 1

No. 13964308) of which the presentinvention is I the drawings Fig. 1 isa view-f half of the an improvement, sl-lows, describes and claims aball with the ribs formed on the outer surface ball having on theinterior thereof ribs integral thereof, preliminary 130 introverting;Fig. '2 is' a with the wall of the ball, serving to resist -inviewsimilar to Figland showing an alternative ward distortion of the walland thus giving the method of arranging the ribs on the ban; Figi 3 ballresilience. in that application, however, the is a View of the half-ballshown in Fig. 1,'afterit ribs are shown in theform of meridiansextendhas been turned inside 0111 F g- Partly ing from either the polesor small polar circles. in-sectionof a ball formed-by joining twohalves, Igfound, however, that such ribs are farther apart like Fig. 3,and shows a wrapping which maybe 15. than desirablein theequ'atorialregion of thelball, applied outside of such ball, while Fig. 5 is asecor if theyare made close enough together in this tional view throughthe finished ball of region there is too great a concentration-ofrubshowing'a cover cemented in place; 'Fig. repreb'ennc'ar the poles. Ineither case the degree-of sents a standard ball to which thewrapping'has rebound of the ball is variable over a-surface, thus n pplF 7 V w, par ly in ec i n,

interfering with its employment where accuracy of ai-ball Of thecharacter described, before said 20 Qfireaction i required, ballhas beenwrapped,whi1e Fig. 8 isa view part- In the present invention I provideribs on the y se t o o e ba f gaft r thesame interior of the ballintegral W'ith'the wall, as has been W pp and C p etedflaim'ed 5111 myPppigr application, but I now ar- The halves (if the 108111, molded aSin 1 01 range these ribs to form anetworkon the inside F g- -O O e'sim'ilar'manner, are cured Sum- 25 of the ball, thus making thespherical surface ciently to cause a permanent set in the rubber. moreunifornily'braoed onth interior. I have found that a three four ths curewill ac- A further advantage of this application in adcomplis'h theresult desired. "The halves are then dition to its uniformity andincreased liveliness introverted as shown n F gd j d lies in thefa'ctthat it may be inflated to retain gether in an atmosphere ofcompressed air of it:

its region between the ribs sphere with a lower omp r tively lowpressure, 11 Which t me the internal pressure than heretofore. This-notonly ba e e ves a fi i u is also possible,

simplifies the operation of manufacture but'is an however, to CompletelyCure halves in the D advantage in the durability of the balls, as thereS oWn in Figs. 1 0r 2, and thereafter turn 35. isless leakage and hence,they remain lively for a halves inside out, place the free es tO- longerperiod of time. gether and cold-cure the joint between them. In makingmy improved ball, I may form the A s the flat on may be by other 'wellkno-wn network of ribs on the interior surface of commeans/ifdesiredpli'ment r halves, Whichimay b sempcured d I The ball of whichhalf is shown inFigs. land 3 40 later'p'laced together and joinedtoforma com: has a l W p' 'fli d W th su an- 40 plate ball with any desireddegree of inflation. tiiilly meridian IYlbS latitudinal ribs -a mid- Iprefer to make the ball by the method here'in qtlato al rib i-3,a di srundisclosed, of forming ribs on the external surface Hing from e juctio P i -O meridian ribs of the halves of the ball, curing the halvessu'ffiwith the latitudinal ribs, to a p int on the equaciently to givethe rubber-a permanent set, then toria'l rib substantially "midwaybetween the me- 45 introverting the halves, or turning "them insideridian ribs. The ribs are formed in the mould out, and joining themtogether by any wellwhich forms the ball so that the ribs are integralknown method. withlthe wall Ill. "The meridian ribs may 'join at :Myinvention comprises also applying an extethe pole '28, or maybeconnected to a po'lar'circle rior mapping to such a ball, tending tocomas'shown in my'Paten't No. 1,964,008. 50

press the ball and counteracting the expanding In the modification shownin Fig. 2, the meridforce. A'ba1l constructed in this novel manner ianribs It), the latitudinal ribs ligand theequarebounds much morequicklyafter striking'a'surtor'ial rib is aresimilar to those in Fig.'1, but in face, and is more satisfactory Where a'veryllively this case'the meridian ribs extend only from the 55. ball is required.p'oleit'oth'e latitudinal ribs l l. The diagonalribs HI extend fromthese junction points equiangularly toward each other to meet at theequatorial rib. This arrangement is substantially equivalent to Fig. 1,with the portions l5 of the meridian ribs left out. In any case, thearrangement of the ribs should preferably be such as to divide thesurface of the ball into substantially equal unsupported portions, suchas are indicated by the character It in Fig. 1 and I! in Fig. 2. Thisgives a uniform bounce regardless of the spot where the ballreceives ablow.

As pointed out in my Patent No. 1,964,008, when the ball is formed inthe above-described manner, (the ribs being first formed on the outsideof the ball, which is later introverted to place the ribs upon theinside) the ribs are thus finally constrained into a smaller space thanthat in which they were given the original cure, and are thus given apermanent compression. This causes the ribs to exert a spring-likeaction in the interior of the ball and greatly increases the resiliencethereof.

When joining together the two halves of the ball to form the completedball, it is preferable that similarly situated ribs on the two halves ofthe ball register to form a continuous pattern as shown in Figs. 4 and5. However, the equatorial .rib overcomes the necessity for suchaccurate registration as is required in my former ball. The "equatorialrib portions it formed on the halves will preferably be of slightly lessthickness than the other ribs, as these two ribs, when placed togethershould form a rib substantially corresponding to all the other ribs ofthe ball to promote uniformity.

The halves of the ball may be joined together in an atmosphere ofcompressed air in the wellknown manner if desired, and thus the pressurewithin the ball may be nicely controlled. I have found that a ballformed with the network of ribs as above described makes a very livelyball, even though just suificient air is placed therein to retain itsshape.

A more lively, though more expensive, ball may be made if sufiicientpressure is placed within the ball to slightly distend the unsupportedportions [5 of the ball surface beyond the normal spherical contour ofthe ball. An outside wrapping of thin strips of cured rubber 30 may thenbe Wrapped tightly around the exterior of the ball, forcing thedistended portions [6 back into their normal contour. The method of thuswrapping a ball is disclosed and claimed in a copending application ofmine. Such a ball may then be finished by cementing the ball over thewrapping as at 3!, covering it with felt, indicated at 32 and giving ita final cure to cure the cement.

In making my improved ball, I may take an inflated spherical ball,having smooth interior and exterior surfaces, and wrap the same withthin rubber bands 39, as indicated in Fig. 6. Such a wrapping with anythin rubber band will improve the ball, but preferably I use a very wideand thin, cured rubber strand which is wrapped tightly about the ball inevery direction and in a suflicient layer to create a compressive effectupon the ball.

Preferably, however, I take in place of a plain hollow ball one havinginternal ribs, similar to that above described. These ribs may be formedon the interior surface of the ball originally, but preferably I use themethod disclosed in which the ribs are first molded upon the exterior ofthe halves of the ball, and sufficiently cured to give the rubber apermanent set. As disclosed in the said applications, the halves may besemicured to the proper point and finish cured when joined together. Orthe halves may be completely cured and joined together by cold curing.In either case the halves are turned inside out after the first curingand secured together, thus placing the internal ribs under compression.

A ball, having internal ribs [0 and II, is shown in Fig. 7, there beingunsupported wall surfaces l6 between such ribs. In one method of makingthis ball, after the halves are completed, their free edges are joinedtogether in an atmosphere of compressed air sufiicient to distend theunsupported portions I6 of the Walls of the ball in the manner shown at24. The best results are secured if the pressure is not sufficient toexpand the portion of the ball carrying the ribs. This is particularlytrue if the ball is formed according to the method disclosed, where theribs are under compression. It will be obvious that any expansion of theball which materially extended these ribs would tend to nullify theexpanding effect or resilient action of the ribs.

The ball of Fig. I may then have a wrapping of rubber bands 30 appliedas described in connection with Fig. 1, thus constricting the distendedportions 24 of-the unsupported walls of the ball back to their sphericalshape, as shown in Fig. 8. This provides an extremely lively ball, asthe internal compressed ribs and the internal fiuid pressure tend toexpand the ball, while the wrapping of rubber bands creates a force inthe opposite direction.

The ball of Fig. 8 may then be finished by applying a coating of cement3| outside the wrapping, and a cover of felt 32 over all, and the ballmay then be placed in a mold for a final curing sufiicient to cure thecement coating and hold the cover in place.

While the ball of this invention is not limited to any particulardimensions, a tennis ball, under the currently accepted rules, shouldhave an external diameter of 2 inches. In making such a ball, by thepreferred method illustrated in Figs. 7 and 8, I propose to first mold aball half having a main wall about 1 inch in thickness, the mould havingan external diameter of 2% inches, this defining the dimension of themain wall of the ball. The ribs will be A; inch outside of this or 2%.,-inches across the outside surfaces of the ribs. Then this half isinverted and joined to another correspondingly formed half in anatmosphere of compressed air, with just sufficient pressure to slightlybow out the thin wall between the ribs but not inflating the ball toover-size. I then wrap the ball so that the bowed thin places arebrought down to the spherical surface of the ball. I then cover the ballwith cement, place over this felt, and put the entire ball back into amould 2%; inches in diameter and cure it enough to vulcanize the coverof the ball. The wrapping, cement and felt add 1% inch to the outsideradius of the main wall of the ball.

This makes a ball having internal ribs which were molded so that theiroriginal outer surface before introversion had a diameter of 2 inches,but which when introverted to place the ribs inside the ball have aninternal diameter of 2%,; inches. Accordingly, the original set of theribs is retained, and thus the outward spring of these ribs, caused bytheir being compelled to occupy a less space than when formed, gives theball the high resilience desired.

While this application is concerned with balls having an internal ribbedstructure, (with or Without a wrapping of elastic strands), reference ismade to my copending application Serial No. 228,093, filed September 2,1938, for claims on a ball having a central sphere with an elasticwinding thereon irrespective of the internal construction of suchsphere. Reference is also made to my copending application Serial No.112,572, filed November 24, 1936, for the method of making the ballherein disclosed.

I claim:

1. A hollow rubber ball having internal fluid pressure, ribs on theinterior surface of said ball spaced with respect to each otherto formspherical triangles, and an exterior covering of tightly wrapped rubberbands to reinforce the portions shape, and means on between the ribs.

2. A hollow spherical rubber ball having a wall, meridian ribs integralwith said wall, a network of diagonal ribs on the interior. surface ofsaid wall and integral therewith, there being unsupported portions ofsaid wall between said ribs, fluid pressure within said ball adapted todistend said portions of the wall beyond, the normal;

spherical surface of said ball, and a wrapping of rubber bands on theexterior surface of said ball to reinforce said portions.

3. A hollow rubber ball having a wall, a network of intersectingmeridian ribs and latitudinal ribs intersecting each other, on theinterior surface of said wall and integral therewith, there beingunsupported portions of said wall between said ribs, fluid pressurewithin said ball adapted to distend said portions of the wall beyond thenormal spherical surface of said ball, a wrapping of rubber bands on theexterior surface of said ball, to reinforce said portions I a coating ofcement over the wrapping and a felt cover outside the cement.

l. A hollow, rubber ball, comprising a wall,

internal ribs on the inside of said wall, compressed to a greater extentthan the said wall, whereby an indented outer surface is formed, andmeans on the exterior of said wall to compress the upstanding wardly,whereby said ball attains a smooth, spherical shape.

5. A hollow, rubber ball, comprising a wall, internal ribs intersectingat points spaced over the entire surface on the inside of said wall andcompressed to a greater extent than the wall, whereby said wall isdistended from spherical the exterior of said wall to compress theextended portion inwardly to cause the ball to assume a smooth,spherical shape.

6. A hollow, spherical, rubber ball, comprising a wall, internal ribs onthe inside of said wall, compressed to a greater extent than the wall,whereby humps are formed'between the rib por tions and adjacent wallportions, and the ball is distorted from a true spherical shape, andmeans on the exterior of said wall to compress the same inwardly,whereby said ball attains a smooth, spherical shape. 7

'7. A hollow rubber ball comprising a wall, internal ribs on the insideof said wall compressed to a greater extent than said wall, whereby theportions of the ball surface in exterior of said wall is distorted froma true ribs having their outer convex boundaries joining the innersurface of the wall and their inner. concave boundaries unattached,latitudinal ribs extending around said wall on the inside thereof andintersecting said pole ribs, said latitudinal ribs extending oversubstantially the entire ball surface, said intersections occurring atpoints spaced over the entire surface of the ball, and especiallyintermediately of the equitorial plane of the ball and each pole point.

9. A hollow rubber ball, ribs on the interior surface of said ball,spaced with respect to each other to form spherical triangles, and anexterior covering of tightly wrapped rubber bands to reinforce theportions between the ribs.

10. A hollow, spherical rubber ball, having a wall, meridian ribs anddiagonal ribs on the interior surface of said wall and integraltherewith, there being unsupported portions of said wall between saidribs and a wrapping of rubber bands on the exterior surface of said ballto reinforce said portions. 1

11. A hollow, rubber ball, having a wall, a network of meridian ribs andlatitudinal ribs intersecting each other on the interior surface of saidball and integral therewith, there being unsupportedportions of saidball between said ribs, a wrapping of rubber bands on the exteriorsurface of said ball to reinforce said portions, a coating of cementover said wrapping and a felt cover outside said cement.

12. A hollow rubber ball, spaced ribs on the interior surface of saidball and an exterior covering of tightly wrapped rubber strands toreinforce the portions between said ribs.

13. A hollow rubber ball, spaced ribs on the interior surface of saidball, an exterior covering of tightly wrapped rubber strands toreinforce the portions between said ribs, and a felt cover secured tosaid ball outside the covering of rubber strands.

14. A hollow rubber ball having internal rubber ribs compressed to agreater extent than the wall of the ball, and a wrapping of stretchedrubber strands on the exterior of the wall.

15. A hollow rubber ball having internal rubber ribs integral with thewall of the ball but compressed to a greater extent than the wall of theball and a wrapping of thin elastic strands on the exterior of the wall.

16. A hollow rubber ball having in its interior circular ribs in theposition of parallels of latitude and ribs extending at an anglethereto, the latter ribs being under longitudinal compression and-serving to support the ball surface at regular

